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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fe4bb9ec3d3bd5fdad4c6aaa52d34810c0530982d66fa5196d508028de0e6bb3' 
  AND token = '3q3AzFJR0RRCXVKmSwuP9bDsCY3uxnq9+P78ev1HOtk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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