SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f280d777dcf7f1cd0adc302b067b43589381c16e25bd2c1e640314bbcdcf9a34' 
  AND token = 'kC93ohRAy2k99HijxIJJgSoQ9kl15ZNwKnwDR32qpjk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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