SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75aa401ae832bae3aa81484bfc8fcc5d40c1b720af39b046caa78e666b00ffe9' 
  AND token = 'hzmnTKRsQcp/CtaeFCdQH4saAaXD+vBjhaZDFQS+9mA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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