SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c20a078fc67712da06a1352ce756ee7626a257dd078a2ab192aac3b56a46e91f' 
  AND token = '6ik1C1jd07RF58eoYSRslNcRXLBFdkmeW7ZCaYVWtjQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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