SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dff5110ee430f28ade01fb7038c1fa39c3a35ddee4e0583f7b78a2add14e7eb5' 
  AND token = 'DsLsjHFsgFOfpBDLJ1hsnLfk6h8PXHZzpRJur5iJYc4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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