SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '6def589bd706df653af2ca54b557a2f157f3a906589339f47fb717200fa6de91' 
  AND token = 'UUQgdXnO2hdowCY+gq5hANgAquZEHqwLzTQVbBVzB8I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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