SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fb4f824d42215773d553eb7935c43f5069ed4f9c4aa6a85cead6f0888a70b54d' 
  AND token = 'W3uvDlUJD/wWzLwnlvVB7HH3tNoOVu4utinZ9X0maY4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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