SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b8e59dc65976235a242358f4676e5aaf7abb32fe804bdb2651089f1e6b476038' 
  AND token = 'li4Nl2efwAtEWnvG1M2duySGDI6aQ+2Y4wZUil2f3gA=' 
  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"
    }
  }
}