SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7fcb340a40747c7a89dcdee99164bd6469d793191ac27e2d8a77c04f8c502321' 
  AND token = 'ZOgyWYT9vCG/ZxwyC6+UWr5v31qxq6poJrOiDgYPo2w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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