SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ec43e3c358a7e2373e415175a20a355618bde6f4e1be3537f57c9d3e26672fdc' 
  AND token = 'c1s3/QbdPPxOVOYT0AneVufkzBfPrsR0T7d5DMI2klg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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