SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3e8e890c9a52eb733f3a89827cc00d50fd42f533c5bc83f6ba335236b70981e0' 
  AND token = 'cInl4/DR033mwU5NdLm3NhHTER4hnEvTo9v6TYmvejg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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