SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '077abf8d1af0f40df29c4c06bde9fde05d9b999be2a7db058a72530048334fcc' 
  AND token = 'pyLDz0I2LDYGALDrfufzKVMd5FxuJrnixtu9q9YplD8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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