SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81e238a37be1934664c3ed8df9811a17b2e1f2cc0b5d785e7518b59b7fc02943' 
  AND token = '01/1UuE9MVzntuYf5Qb5gDfvnJYUl9WOjQKB3yt/Gz0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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