SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '781aa57e5a16dc60e3a721b3dc7ac137fca5979d8ccbd51000f79eec723828ad' 
  AND token = '954hxkP0SufQbLJWMGFS5ERM7BerfFchHUAJrLdByo4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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