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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ab4b7da306b21a5d2d0401e743bb1c614ab9575815a88efa9c7a6968a353d8e4' 
  AND token = 'Km6quvKQs9gLIfGE2lgSoroUAgW7GZiMoKdXiS3IC+Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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