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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '947bf5e66d68ae29347c55f45e56701de18785790259df0e90a428fa57a7cef4' 
  AND token = 'MmsdfCwFZTPIfYkt2OdDqwrtAxEq7XgmF41i/H3AUcY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}