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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fc7d3fd30aee635a0e25933d2f1e15a76bcc81744eec60eead65f366c00ab35b' 
  AND token = 'f5HhwZMW3V4UZLpQXdiDOK4oB2KZa3+BTKlZ4h0mKgQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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