SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '478a305788f6d8dca71923a758eb100875a7e7d122b355f7e0db62809e3e4254' 
  AND token = '2Z0a/NnfFNWk1TNOl93rnwgnUCoAR5YRBm4+251AHVI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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