SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df75e7877b248028c3e11b2968d23b5fb69ef47929f8334fdcdf26c9c0afd8d6' 
  AND token = 'KzV9poUv5HOGAb0Ooo1RK5shhuNhJwOodQ+bTX7RUIY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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