SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f7b176ed4a6f9a29662202f030740058019d8768527362ebb28f35386a13cc02' 
  AND token = 'n44ig99flTrVEKuXK8qrdNuSE3rbrmRDkBo1SuCnGhI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}