SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a700c6de73eb904aed5825618037799ab6ff57fac3a91908e42dee6197440286' 
  AND token = 'X1kVV+cz+AK4rk4iR4OzoVHf9Lx1CLqTcIgfbPKO1NQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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