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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5ed38dcf24ee29ef3818d7deae784fef5c016f5537019dc3f7dddf1cdd940a8e' 
  AND token = 'nKN8U2OrAQzvbAPEQy6P4cYqnbbBPEAEFJN3sr+WhTs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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