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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ec93ec4fb9c734754819911337ca9f152bd7f3635fbcaeddb193d2dc996916c9' 
  AND token = '5rmFo8VugO8YovIF6fJiENhfhFBzzDpi5MGQsaXxW/I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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