SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ff10cfaccffa2c5966f01e5539e8bb5678d3c5e30dc3b695ce56f1992ea3bf75' 
  AND token = 'UH/piHsPONjQq2q0c3uNSPN7SKwoAzXHD5VVPMy2+gE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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