SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7feb2bab4563439754798724820ccaed49134884d869e4abb13e925beb4caa44' 
  AND token = 'B/d73IAjJnROud9tcXpD4dYc6gGsr7P9CVjtiLRlflE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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