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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3de5915560f467ec7c59a7afc8c8f3c135d11e6e555b18bcb66d92903938dfff' 
  AND token = 'Mb/CvCR5v21n1Cq2r1CrZlBuwSy+hWnEA0c8FRFQR0s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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