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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df1b851d2ed41a1806a63088a4a38691d35cde83dad0570f4dc94c0244a57c36' 
  AND token = 'uYcJW5ZtUzUeoc5fioOgIUHafsBZA980VIYge6/Jllg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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