SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9dff405b047c458e28b03171418d161831086f218e121a05a9aeb1f32d610d63' 
  AND token = '3t40C7h/VCcLtUUdjrFpURjY7Lk2s0rLuDrL9gJxpV4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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