SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50ca6e4862b104a4dfc46edcf3b22236a8391e8fec0c5a5ed639394da735157e' 
  AND token = 'hPy7IAGPG/uoxjrFfcmWeLZ55qr6WWc5Y3ahFGfNR1k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00070

JSON explain

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