SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'a9861eea49748e48f6a2b8483362501d9530038d4b9b1592a174fd669e631850' 
  AND token = '5rfHTGT+2n/3NRUfx6qn9tNS6IkAGTz5aX68l7a7Xrw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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