SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a0519ee5b33c68c2375e54df8364222c98d9b3883e0d8035fb8bd516dd3325a' 
  AND token = 'mxPDOpV0D6ZE71e73b7jSJxV1GLf1ZHnvRjCSG2kdKw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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