SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c7c6274280ab5054ee3fdc9e7547dfddbfadf037205abc2371179e2b74b2c079' 
  AND token = 'MaDkH1nIJJujVYrAp2vafJ4j+wp+fhlCCCK/Kovpq7g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00055

JSON explain

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