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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0d78b842397980466405249a78b01e16397bcc50c79e54f9c8ad48186c5a69ca' 
  AND token = 'kx1qpreweK5ESt6TLSpEm34aTS2b9vOKpY7WArUS3EE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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