SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '7e19c600366a071f6e9f285211916b7a0c497c7ba12cffe6db3e053848d1bc54' 
  AND token = 'rs6zNuI2SWa9jbLKRjgoU70bVmKmHI6HrHketorH2jI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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