SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7c935f264f945722cb29035a2688388e81fe0890193f85a13471f4a7bf789837' 
  AND token = 'rL3gYoNJFABMF0Q2eSIb4FLvNt+UIqG/Pq4WN9CVczg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00053

JSON explain

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