SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '57c944cfa1103c06c4171b54bb68719d8c0201cb316312dc508b7ab06bddadd6' 
  AND token = 'xitQI+FlIPVkKKGap4ct1FDLq4pqT8w3JXztalwDeXo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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