SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '85c135d382b385519a738fa045d35dce1a4f3a23028475b96174e607b9a84a2d' 
  AND token = '3knVUXeKc+is97It0X2JcozkX29I79iKeNMgBCUjpS4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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