SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f12abd676fa6520b26137619568208c2feee9a082508a24411502d9ef228ea72' 
  AND token = 'vjOkWZ0rD6pAB1BNhXCKEvqt4EpuiPbis+2DCCzHGnw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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