SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '17204d809f8d221ab97a998211c7975dd2d584b513beb913b6db29c3be439f40' 
  AND token = 'SA6Z+0jaYrfsjbEv5MLGLqzW1GbPWwQQC3PXhIR/4eU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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