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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ef83819122ddf53052f7a7ecdee59cb9f6621509cddd4d443679e312f0762a02' 
  AND token = 'l9vTkdfJQ4XYfy8PCXd52A+z1GRHhe6ktOJ8UY/Jv1s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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