SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f75d6c1814232c73f6a72f0fe9960040e3b4594c8fb7ad61a32523d45244541' 
  AND token = 'fb4yE14ILj21/dQbLAUHBMDVyGmvjG4h/DfOeIzvj88=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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