SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2ff7785c5def2cfbba547320c1c73128212f5ee5c65c4d3537fd90b06561b6e9' 
  AND token = 'RgKziDFBWH42Nt5ZBKgxNufdD+r8edVbGVmpdy39UFc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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