SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '21cf3b77abf6fa4c0a1f252ed86002b791ab88e8926eba7bc85df827d68733f5' 
  AND token = 'ZlmNLNRK3Q3EiYoHQ+lPAh1indxzY4Q/WaB8oLxV5fE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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