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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c39de5a67c7761aa83f7cd1bb0fa1e6f4e0d9d06540e72edd29f829c7b2d7447' 
  AND token = 'PFyLhFpyGAzJ92cJOF5lIIG3FwHZSYK2hzXUr9afAQc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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