SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2b7f663b9b937cfb7e703bf1f5484a2476b7db5217dd1dfaacdb64c1fbf7ef46' 
  AND token = 'cxBWEwEeVKhduzBq2gbcdzzGs5VB7xm7Sp+5eKTdlaU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00054

JSON explain

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