SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '811bf785432e43b7b3688994e5b051a2614d551e2f89d3b896a0a11824f5cf63' 
  AND token = 'JmYAyFW4vdqDgMZSKs7eXLyYOIRM+ITbiTVgA07wGrQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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