SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76dc0b9c119d6b0f8916fab28265216f33d1afb41694ebf61db35cbd1014037d' 
  AND token = 'KTO+2xQyWdc/6vWee3mvlstb9NQ/HHE9zBVAMY/Ga3Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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