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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'e1e62f267871b2c44c5170759caf37f2877edd6c8c6c84f18a735c6e467d8f42' 
  AND token = 'Wkp3odDk4QIQlWh/++zcwoU7WC3lTsA16Vq8bwVynvk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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