SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '19a20cfa971fadca89a28544e2ee240729ced5636181a3706340fbb91986ff75' 
  AND token = 'Yra8kmqZMrxpXQBLOAiMgVZgdFJyUUoZ6b13+WHf+5s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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