SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c2868b64ba4bcfaa63847fa930c9797616c06ea972a1c6b008fb0124a345d60a' 
  AND token = 'PPJbWiRazrVZdtTnHIRR0aIlnIZpsnjsmN2m88H1UsQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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