SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6556c9fecf35bdb89977e65537089ad2a8912b42e1de8629dc0745a5ed4d251f' 
  AND token = 'GttvMHsfSJrE33xZFXXMaSnsL3hCNQ3+svXP6zZNia0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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