SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a0ef59dfb2117dcb831818e1a2b54413c678231c4b0f09a93844a197a4b54372' 
  AND token = 'sz5L6av8VaVGRTobdCM8Kb+6bW1WHvCGZbMHt0nquZw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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