SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a632ee7c51d9cca74e8c6405990bc1adf0b074846a83f91b73f5445574a1aba2' 
  AND token = 'r69w55Zk2RgyLM7AdMaFWFfujRZ2Ncos4wAhJLJdaq8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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