SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '55cd664c0747f9ef19305f1f0b05da48fac1b839c05e237f853db226b1efdb87' 
  AND token = '+9wiwz/8EIZsIirh0yFEe9Jli0n1vwMjhUOTVZDBUQI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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