SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'add79e313497cb599bf154473e4dd9078fa8c588bf4d2e14f2c9498a75572008' 
  AND token = 'EuspbBhnKYMLxZjrBHXLUVpHyyTTcXpS6g/nj6V1aN8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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