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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '759d27f2340b0c8138fa74844f13fbe6a96826e8c1b514f8c6bf19da797fe7d9' 
  AND token = 'QS72fcVSYANfj9jKVYFJmgLNYJeSlB95ZaS65Fd93Ig=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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