SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eb6acd23708094fbfd3222245302159998119af8551fc9167575d10f2ca5d2a9' 
  AND token = 'uB3uj5ZipWxNBFy4vCileea5Rt9C0HGPtqTrbb8qGfE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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