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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b256444b58e4d0cf754113cc4a1374a1bc204b7ff32d39780de0a256dae3bfb5' 
  AND token = 'DimSJ5gc3vA8ivrO1qXvj90a6SK/z+pg6iaDgaNg/6Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}