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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b0b3e079482ba55a51a087432a1ccd6f4e729d2af5f3024702fcdb7ec6ce54c5' 
  AND token = '6qB2P2dh6ZG0M8TumBcUUf+G13BoyRYe2L5rhb8mqqI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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