SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '681cc010a517ff20fe4315989b818cddfe4e5d53b4af45151266ce0ffa9ab3e9' 
  AND token = 'ak63RL2NR4c6Vpd1jCLGFYM4HEs8vV2ESUcmINQVlKQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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