SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '30c1d976269448b5ce6173513dcede0cb71c64d0b988b57dccfe196558708191' 
  AND token = 'e1QnOcsQuQoVlkthyBSrCn+nuCJBUGIU8f3Sutcb6CI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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