SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4978f3a6e939fbba2be9701f5845571096d10ff9e2a7c4769c49d98abf8d9bdd' 
  AND token = 'IQHbpKa18Ua0QJAkvgNiWUh0Gu4aPZMf+ef8HYM51e0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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