SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9c38400443a23ddbbde56fd8546043eb78189410a2672c0c57e4c7ebf91052cf' 
  AND token = '8Rd5GXWzO6gLZqlNq05OkYrWPkwTj3aEwbUxTfzItEQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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