SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0c8a8aba4755aa507ddfd4e2541ba32ac9fbeac115646e62696080c203d67d51' 
  AND token = '0NyQq6t8FVz4hbA0lottjCu6aCXSmBH2+5gYYClzgPo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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