SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e8dd87d6cd0ba64d1e794a01e90acd800f545db711db8823e50195d92613ab02' 
  AND token = 'xSv9FKxug0vLVxWkv6vkt1V31wTzZnaabvKO4gWm2Yw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}