SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'af7d4130d1cc9a12fb32fc3c377433c7562f96c4ef5cf6d05e1856728b1e1e5e' 
  AND token = 'nVIwav5B8NZCzt7PzQP4sm/4/hY2BdUaDhPF+4G+Rng=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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