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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f0e642a5691ec564f6008d000e1115ffbb8537d75fe661effd41e05b5aec9a04' 
  AND token = 'uvvXgpeLU/QBftTJ2rRY7uQ/qY7ev9Czm7AEbnT7lgs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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