SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c3328cf75e546796c06dee45847962f5a4f4412934d7f3eb603190e51eeefec2' 
  AND token = 'rB8aW1z2/+uqLZh5VRD8sx/ooGgRXmBxfYHLNP8PwVg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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