SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'f4aa8398d877e84f6a88a2c47a87fb80896032e5b3f8859d7cb88ee8207775f7' 
  AND token = 'ov3c3BrTraYaI6yMlqDHfDBSbfWxmsLUEUmgqonzP8A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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