SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b5112581616b83e981d513def86a2a05552e51bc649907bb85f18bee39136a29' 
  AND token = 'oFjc34aph11WrPN+i0ynhsZ9dmYEAOsXSohl0Kz6+nI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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