SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '8f0a10f8f25b2815a015a27b7cabc386a935ec2eabb8be5e3e7a40019551fba6' 
  AND token = 'Z/ver+gfhuhIIW/tzmBnFWsqlSbCVVjNC++EvTwJHis=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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