SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c11a12bdef50bf8069824e1e7f21aa6eff38511e90360533be0b6f77546e280b' 
  AND token = '3xO3KvDoWH1nZkdKf5JZLGFOGM01qt0wLSBJni1RXqQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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