SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3c136d749645a707671ede14ea02685bdeaf6ccd096b88e71d80b72b1e51312f' 
  AND token = 'WkX50Z/SDRF7hTyC4VSsfmaDj9/zB0QJLcUFHJvt45w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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