SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dee50f58c0503df348677681b23203e63a8451adbb4720b011ad7479f5d5ad1b' 
  AND token = 'BU8oTByjL+KoBeCmrER0QJ89pEHkngznGrL4uK3Jfvw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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