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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c79b4ed6bb87188b2b3778dedd66d5d3bffdf3bc97c257f67f88c8fadcbc4d15' 
  AND token = 'kH7ZSSfpTL3ZxYtua5uPk0QKJI+dWVvHgAULCTDPB6c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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